MOLECULAR EVIDENCE IDENTIFIES BLOOM-FORMING PHAEOCYSTIS (PRYMNESIOPHYTA) FROM COASTAL WATERS OF SOUTHEAST CHINA AS PHAEOCYSTIS GLOBOSA

Chen, Y. Q., Zhou, H. & Qu, L. H. Key Laboratory of Gene Engineering of Education Ministry, Biotechnology Research Center, Zhongshan University, Guangzhou 510275, P. R. China Sequence data from the 18S small subunit ribosomal RNA gene and rDNA ITS regions have been used to identify the species of a Phaeocystis (Prymnesiophyta) that caused harmful algae blooms in the coastal waters of southeast China. This Phaeocystis has morphological and physiological features that differ from those previously described for either P. globosa Scherf- fel or P. pouchetii (Hariot)Lagerheim. However, the sequence comparison of the Phaeocystis 18S rDNA and rDNA ITS clearly showed that it was remarkably similar to several isolates of P. globosa. Thus, the species isolated from the southeast coast of China is identified as P. globosa rather than P. cf. pouchetii or another species. Our results also demonstrate that phenotypes of different members of the genus Phaeocystis are variable, apparently changing in response to environmental conditions. It is concluded that, on the basis of this phylogenetic analysis, the bloom forming southeast China coast species of Phaeocystis most likely originated from an endemic warm-water, rather than a foreign source.